3GPP (3rd Generation Partnership Project) is a standardization project that considers and generates specifications of cellular mobile communication systems based on networks advanced from GSM (Global System for Mobile Communications) and W-CDMA (Wideband-Code Division Multiple Access). The W-CDMA has been standardized by the 3GPP as a third generation cellular mobile communication method, and services thereof have been provided sequentially. Additionally, HSPA (High-Speed Packet Access) with the higher communication speed has also been standardized, and services thereof have been provided. EUTRA (Evolved Universal Terrestrial Radio Access), which is an evolved version of the third generation radio access technology, has been considered by the 3GPP, and the Release 8 specification has been completed at the end of 2008. Further, consideration of Advanced EUTRA (also referred to as LTE-Advanced or LTE-A), which is an advanced version of the EUTRA is in progress (Non-Patent Document 1).
For the LTE-A, carrier aggregation (hereinafter referred to as CA) technology has been proposed as data transmission technology which maintains the compatibility with the EUTRA and achieves the speed that is equal to or greater than that of IMT-Advanced (4G) (for example, Non-Patent Document 2). The CA technology is such technology that a mobile station apparatus simultaneously receives signals transmitted from a base station apparatus, using continuous or non-continuous downlink component carriers (hereinafter referred to as CC) each having a small frequency bandwidth (for example, 20 MHz bandwidth), and generates a pseudo carrier signal having a large frequency bandwidth (for example, 100 MHz bandwidth of five CCs), thereby achieving high-speed downlink data transmission. Similarly, according to the CA technology, the base station apparatus simultaneously receives CC signals transmitted from the mobile station apparatus, using continuous or non-continuous uplink component carriers each having a small frequency bandwidth (for example, 20 MHz bandwidth), and generates a pseudo carrier signal having a large frequency bandwidth (for example, 40 MHz bandwidth of two CCs), thereby achieving high-speed uplink data transmission.
(Relationship Between Introduction of CA Technology and Combination of Mobile Station Apparatus Configuration)
A combination of CCs for the CA technology depends on various parameters, such as the total number of uplink CCs (for example, two), the total number of downlink CCs (for example, five), the number of frequency bands (for example, three frequency bands, which are 700 MHz band, 2 GHz band, and 3 GHz band), continuous or non-continuous CCs, transmission modes (for example, FDD, TDD), and the like.
FIG. 34 is a schematic diagram illustrating an aggregation of CCs according to related art. In FIG. 34, a horizontal axis denotes frequency. Additionally, FIG. 34 shows a case where there are two frequency bands, which are a frequency band 1 (2 GHz band) and a frequency band 2 (3 GHz band). Further, FIG. 34 shows cases 1 to 6 separated in the vertical direction. The cases 1 to 3 show cases of a FDD (Frequency Division Duplex) transmission mode. The cases 4 to 6 show cases of a TDD (Time Division Duplex) transmission mode.
In FIG. 34, the case 1 shows an aggregation of CCs where three continuous CCs (center frequencies f1_R1, f1_R2, and f1_R3) are selected in a band 12 (downlink) included in the frequency band 1, and two continuous CCs (center frequencies f1_T1 and f1_T2) are selected in a band 11 (uplink) included in the same frequency band 1.
The case 2 shows an aggregation of CCs where two non-continuous CCs (center frequencies f1_R1 and f1_R3; Intra CA case) are selected in the band 12 included in the frequency band 1, and two non-continuous CCs (center frequencies f1_T1 and f1_T3) are selected in the band 11 included in the same frequency band 1.
The case 3 shows an aggregation of CCs where a CC (center frequency f1_R1) is selected in the band 12 included in the frequency band 1, a CC (center frequency f2_R1) is selected in the band 22 included in the frequency band 2, and a CC (center frequency f1_T1) is selected in the band 11 included in the frequency band 1. The case 3 shows that two non-continuous CCs (Inter CA case) for downlink communication are selected from different frequency bands 1 and 2, and one CC is selected for uplink communication.
The cases 4, 5, and 6 are associated with the cases 1, 2, and 3, respectively. For example, the case 4 shows an aggregation of CCs where the band 12 is used for downlink/uplink communication, and CCs are selected according to time bands. The case 4 shows an aggregation of CCs where three continuous CCs (center frequencies f1_1, f1_2, and f1_3) are selected in the band 12 for downlink communication, and two continuous CCs (center frequencies f1_1 and f1_2) are selected in the band 12 for uplink communication.
Additionally, regarding non-continuous CCs in the same frequency band (for example, the center frequencies f1_R1 and f1_R3 shown in FIG. 34), there are three following cases: a case where multiple base stations transmit transmission signals while synchronizing timings of frames or the like (referred to as inter-base station apparatus synchronization); a non-synchronized case where each base station apparatus transmits a transmission signal independently; and a case where a channel delay occurs even if inter-base station apparatus synchronization is performed, such as when timing difference occurs among frames of OFDM (Orthogonal Frequency Division Multiplexing) signals, thereby causing non-synchronization.
Further, regarding transmission by a base station apparatus using continuous CCs (for example, the center frequencies f1_R1 and f1_R2) in the same frequency band, various technologies have been proposed in consideration of elements, such as the backward compatibility with the LTE system, the radio channel raster of 100 kHz UMTS (Universal Mobile Telecommunications System), a guard band between two adjacent CCs, guard bands on both ends of continuous CCs, or frequency use efficiency (for example, Non-Patent Document 1). In the case of continuous CCs, however, the length of a guard band between two adjacent CCs is not the integer multiple of the 15 kHz subcarrier bandwidth. For this reason, a separated baseband processing circuit is required in a transmission and reception circuit in order to maintain the compatibility with the LTE system.
To cope with the above various situations, the configuration of the mobile station apparatus depends on the following elements: (a) the number of frequency bands; (b) the total number of downlink/uplink CCs; (c) continuous/non-continuous (Intra CA/Inter CA) CCs; (d) radio transmission modes; (e) inter-downlink CC or inter-base station apparatus synchronous/asynchronous transmission; (f) various CC bandwidths (for example, 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz); (g) the bandwidth of multiple continuous CCs each having 15 kHz OFDM subcarrier bandwidth (for example, 100 MHz); and the like (for example, Non-Patent Documents 2 and 3).
(Relationship Between Another Introduced LTE-A Technology and Combination of Mobile Station Apparatus Configurations)
As requirement conditions for the LTE-A (Non-Patent Document 4), the data transmission speeds of 100 Mbps for downlink and 75 Mbps for uplink are required while a mobile station apparatus moves at the high speed. While the mobile station apparatus moves at the fixed speed, the data transmission speeds of 1000 Mbps for downlink and 500 Mbps for uplink are required. To achieve these transmission speeds, the high order MIMO technology is introduced other than the introduction of the CA technology. For example, downlink 8×8 MIMO (the number of transmission antennas of the base station apparatus is 8, and the number of reception antennas of the mobile station apparatus is 8) can achieve the data transmission speed of 1000 Mbps in the 100 MHz transmission band. Uplink 4×4 MIMO can achieve the data transmission speed of 600 Mbps in the 40 MHz transmission band. Additionally, CoMP (coordinated multipoint) technology for communication between base station apparatuses and uplink transmission diversity technology are introduced in order to enlarge the data transmission speed of a cell edge or to enlarge the cell coverage area.
Therefore, the configuration of the mobile station apparatus also depends on the following elements: (h) downlink/uplink MIMO methods; (i) methods of CoMP communication between base station apparatuses; (j) uplink transmission diversity methods; and the like.
(Relationship Between Carrier Operation State and Combination of Mobile Station Apparatus Configurations)
Frequency assignment for the IMT-Advanced has been determined at the world radio communication conference 2007 (WRC-07). However, all of the current IMT bands (Non-Patent Documents 4 and 5) are not common to each country. Each mobile telephone service provider uses the frequencies individually assigned to the country of the provider. According to the state of frequency assignment to each country, the mobile telephone service providers use different transmission modes (TDD, FDD). Additionally, the integration of different transmission modes (for example, mixture of different transmission modes between a macrocell and a microcell, between an in-door area and an out-door area, or between a cell neighborhood and a cell edge) has been proposed. Therefore, the configuration of the mobile station apparatus is more complicated in further consideration of the following elements: (k) the state of frequency assignment to each mobile telephone service provider; and (l) domestic/international roaming (Non-Patent Documents 6, 7, and 8).
The above elements of (a) to (l) have not caused significant effect on the configuration of the mobile station apparatus in the mobile communication system of the related art. For example, regarding the LTE system, categories of the mobile station apparatus (UE categories; 5 types) can be defined by the buffer size of data processing software of the mobile station apparatus (maximum downlink data speed of 10 Mbps to 300 Mbps) and the maximum MIMO configuration (1×1, 2×2, 4×4). Once this category is determined, the configuration of the mobile station apparatus can be fixed. In other words, five types of mobile station apparatuses may be provided to each mobile telephone service provider. Additionally, five types of mobile station apparatuses may be distributed in the market.